1. Field of the Invention
This invention concerns a berry harvesting machine, especially a grape harvesting machine, of the type with a harvesting head comprising two berry detaching assemblies placed face-to-face and consisting each of a plurality of superimposed picking arms or shakers.
Said vertically spaced out shakers consist of flexible bars and are attached, through their opposite ends, on one hand, onto a vertical activation shaft, and on the other hand, onto a fixed vertical shaft, either oscillating or rotating freely.
A vertical space, usually designed as “pinch” is provided between the two berry detaching assemblies or shaking assemblies.
The invention concerns more specifically the mechatronic shaking control for the shaking assemblies of such machine.
It also concerns a mechatronic shaking control method.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The world of viticulture is today constantly looking for solutions to improve the various harvesting systems of grape harvesters.
For a few decades, many solutions have been proposed to the wine growers who use mechanical grape harvesting, or to those who used to harvest by hand and became mechanized based on the harvesting quality level achieved with modern grape harvesters.
However, the quality of the grape harvest achieved still remains highly random and depends on several parameters, including human assessment parameters and mechanical performance parameters of the systems that make up the harvesting head of such machine.
With regard to human parameters, significant progress has been made in the ergonomics of the controls for adjustment of the harvesting part of grape harvesters. For the harvesting head adjusting part, three main separate assemblies can be considered: The vine shaking part, the harvest conveying part and the harvest cleaning part. These ergonomic accesses to the various adjustments of a vine harvester harvesting head enable the vine growers to apprehend much more quickly the adjustments so as to obtain the best quality results for the harvest.
With regard to the mechanical performance parameters, many improvements have been made on the three parts described above, and more specifically on the vine shaking systems.
The vine shaking system is by far the most important part of a grape harvester harvesting head.
It is indeed easy to understand that on a harvesting head, one part of the systems is designed to correct any insufficient quality generated by the other systems. For example, the vine cleaning system must be all the more performing as the shaking system is less since it generates a lot of leaves and plant debris of all kinds that are to be eliminated.
Several control systems for harvester shaking systems, such as self-propelled or tractor-drawn grape harvesters are currently well-known. These control devices are more or less sophisticated depending on the various constructors and the performance levels sought.
Regarding the grave harvester shaking systems, one must take into account that they comprise two separate parts:                On one hand, the shakers that transmit the vibration onto the vine to make the grapes fall in the best quality conditions possible, and        On the other hand, what is called the shaking control, designed to activate said shakers in a more or less controlled manner and with more or less precision.        
There are at the present time two main types of shaking controls.
I—The Common So-Called “Conventional” Shaking Controls
These are non adjustable or little adjustable shaking controls. They generally consist of a crank-rod system and do not allow for the basic adjustments that are adjustment of the shaker amplitude and adjustment of the pinch between the shaker assemblies, except for a manual or semi-manual adjustment directly on the shaking control. The shaking frequency can be adjusted at the operator's station on most shaking controls as this adjustment is very easy to make and most of all inexpensive. It is generally made using a hydraulic motor that drives the crank system in rotation. The crank rotation speed gives the number of strokes per minute for adjustment of the shaking frequency.
The so-called conventional controls have the verybig advantage ofbeing simple and sturdy. This is the reason why they are greatly used by the various grape harvester constructors. Their designs are very simple and require only very little electronics, or even none at all. Since they are all made from a crank-rod system with continuous rotational motion and an associated flywheel, they use very little power as, once started, the shaking faces as sole opposition the vegetation, it being understood that the rotation is continuous and smoothed by the flywheel.
On the other hand, the so-called conventional shaking controls with a crank-rod system have the very big disadvantage of being very rigid controls; i.e., regardless of the conformation and hardness of the obstacles getting into the shaking system, the crank-rod system never stalls, at the risk of mechanical damage. The reason for such damage is that, since the stresses generated in the rods cannot be controlled especially when they occur at the top dead center of the crank-rod system, it is difficult to size the mechanical parts so as to ensure reliability of the shaking control regardless of the obstacles getting into the shaking device.
The so-called conventional shaking controls with a crank-rod system also have the disadvantage of not being easily adjustable. Three main adjustments necessary for a shaking control are namely to be noted:                1) The shaking frequency adjustment is generally done using a hydraulic motor.        2) The adjustment of the pinch between the shakers: such adjustment is usually achieved through manual adjustment of the length of the connecting rod on the crank-rod system of the shaking control.        3) The shaker amplitude adjustment: this adjustment is especially difficult to achieve especially with a crank-rod system. It is indeed easy to understand that the only way to vary the shaker amplitude is to vary the radius of the crank, or to vary the connecting rod attachment position in relation to the rotation axis of the shaker activating shaft.        
II—Electronic Shaking Control for Selective Harvesting
This control is described in FR-2 768 016 document.
To date, this control has been the best performing in terms of adjustments at the operator's station and of accuracy achieved. It permits to adjust all shaking parameters at the operator's station and in an accurate manner, including adjustment of the shaking frequency, adjustment of the pinch between the shakers, or adjustment of the shaker motion amplitude.
This shaking control has namely the peculiarity that the right side and the left side of the harvesting head are not mechanically coupled, which makes it easy to adjust the pinch between the shakers of both shaking assembles, i.e., between the shakers of the left assembly and the shakers of the right assembly.
The shaking control described in FR-2 768 016 document is not a control with a crank-rod system; it is activated by a hydraulic alternating jack system controlled by servo valves.
This hydraulic alternating jack system controlled by servo valves is a very big advantage not only in terms of adjustment, but also of flexibility. Contrary to a crank-rod system, this shaking control can indeed partially stall on a significant obstacle, for example a thick vine stock getting into the shaking system, which is usually an advantage. On the other hand, if the vegetation is very dense, the system may lack power and continuously stall, which is very problematic and limiting.
Since each right and left shaking assembly is independent and hydraulically and electronically controlled with precision, all adjustment possibilities on a control of this type can be considered.
The shaking control described in FR-2 768 016 document still has a rather serious disadvantage consisting of the fact that the absorbed power is much greater than that absorbed by a conventional crank-rod system. The overconsumption of power is approx. 40%-50%, which can prove to be a big problem, especially on low power machines, including on tractor-drawn grape harvesters that are usually drawn by low power tractors. In addition, this extra absorbed is transformed into heat in the hydraulic oil that must then be cooled, which is an additional economic disadvantage.